


Loving Mother

by Sir_Skullian



Category: Undertale (Video Game)
Genre: Child/ Adult relationship, Commissioned Work, F/M, Fingering, Masterbation, Missionary, Mostly Fluff, Mother/ Son relationship, Porn With Plot, peeking
Language: English
Status: Completed
Published: 2020-01-06
Updated: 2020-01-06
Packaged: 2021-02-27 15:27:59
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 4,392
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22139311
Author URL: https://archiveofourown.org/users/Sir_Skullian/pseuds/Sir_Skullian
Summary: Frisk awakens one evening to the sound of Toriel crying in her room. He goes to see what’s the matter, and learns that Toriel is lonely. Frisk makes it his duty to help his adoptive mother never feel lonely again.Commission for an anonymous friend.
Relationships: Frisk & Toriel (Undertale), Frisk/ Toriel
Comments: 6
Kudos: 34





	Loving Mother

**Author's Note:**

> This story is an AU where Frisk never left the Ruins, and instead was raised by Toriel. The two develop a relationship with one another as a result.
> 
> [EDITED] I don't do Underage stuff on principle, and it's unlikely that I will in the future. I just did this for an internet friend who was having a bad day and practically begged me to write it for them...sorry if you want more, but I probably won't deliver...

Frisk sat up from his restless slumber, reaching for the flashlight on his night stand for protection. It had been three months since he fell down into the Underground, and after a run in with a homicidal flower, he was saved by an anthropomorphic Goat woman named Toriel. Toriel radiated a warm, loving energy, with a smile that showed she had love for all. She gently asked Frisk if he wanted her help, and being scared and alone Frisk accepted, taking her furry hand as she led him through this strange new world.

She took him in, protected him from the various traps and dangers of the underground, and even taught him a few valuable life lessons along the way. Her comfort culminated in her home, where she gave him food, a place to sleep and became a doting and loving mother, and all she ever asked was that he not leave her side.

At first, Frisk was hesitant. She was a stranger in this even stranger, underground world full of antagonistic flowers and creepy looking Froggits, but as the days passed them by he began to accept his life here, trusting her as she cared for him and kept him safe from the dangers that lie just beyond the walls of her small home. They would forage for mushrooms, vegetables and snails twice a week, using them in the various dishes they would share. And every night, just before bed, the two of them would share a slice of butterscotch-cinnamon pie, his new personal favorite. Occasionally she would make herself a snail pie, but after one taste, Frisk vowed to never again eat the confection.

Tonight had started much like all those other nights. Toriel and Frisk sat near the fireplace, half a slice of pie between them as the heat from the flames warmed their bodies. Frisk had fallen asleep on the floor after finishing his slice, and Toriel gingerly picked him up, brought him to his bed, and tucked him in with a tender kiss on the forehead. She whispered a solemn good night to her precious child before closing the door, and there, Frisk lay asleep.

Or rather, that’s what Frisk had hoped would happen. Late into the night, Frisk thought he heard the unnatural cries of a Ghost. He’d heard Toriel tell him about some Ghosts who lived in the Underground, but he’d never actually seen one, and the thought of encountering the Monstrous Apparitions scared him to his core and shook his bones. He tried his best to sleep, but every time his eyes would grow heavy and he was about to dream once more the moaning cries would call out again, shocking him awake with fear.

So now, flashlight in hand and eyes forced to stay open, Frisk looked about his room in a tired panic for any signs of movement. The ghostly wails continued every so often, but as he listened closer to them, he realized that they were not quiet ghostly sounding…they almost sounding like…crying.

Frisk listened intently, trying to pin point where the sound was coming from. Standing now in the middle of his room, Frisk could hear it coming more from his left side, and he placed an ear to the wall that connected to Toriel’s room. Sure enough, Frisk heard the crying more easily now, and a pang of guilt hit him. Was Toriel crying…because of him? Was it something he had said…or did? Was it because he refused to eat Snail Pie?

Frisk, wanting nothing more than to help the woman who had so selflessly helped him, made the decision to see if he could help. He grabbed his flashlight, made sure his clothes weren’t too wrinkled, and headed for the door.

Quietly as he could he turned the door knob, snuck his way out his room, and closed the door gently behind him. Her room was right next to his, so he wouldn’t have far to travel, but even so her gently tip-toed with his socked feet across the wooden floor, taking care to avoid the few boards he knew creaked when they were stepped on. He reached her door, and unsure of what to do next he placed an ear to it, making sure his suspicions were true.

Toriel’s cries met his ear, and he knew he had to do something. He grabbed the door knob, turned it ever so slowly, and gently creaked open the door to peek inside.

Toriel was sitting at her desk, a single candle lit to illuminate the room. She was slumped down on the desk, her head buried in her arms, and she was weeping quietly into them, sniffing occasionally. Scattered across the desk and on the floor were various photos, and the picture began to become clearer in Frisk’s mind.

Photos of Toriel with a large Goat man and a young Goat boy. Standing in front of a restaurant called Grillby’s. Staring about them with wonder in a cave surrounded by bioluminescent blue flowers. Overlooking a massive castle in the distance as they all hugged one another lovingly.

‘This must have been her family from before,’ Frisk thought to himself, the door open slightly more so he could more easily see. More pictures caught his attention, but one quickly became his focus. In Toriel’s hand, just barely in view, was another family photo like the one from before. Only now, standing next to the young Goat boy was…a young Human. No older than Frisk was now, who he shared a striking resemblance with.

Frisk’s gaze shot back up to Toriel, who had quieted suddenly. She sat up and stared at the picture, tears still streaming down her face. She held the photo close to her chest with a sad smile, and as she placed the photo back on the desk she began to turn to pick up the other photos.

Frisk immediately went into a panic at the thought of being discovered, and in his attempt to quickly and quietly close the door he lost his footing on the wooden floor. He fell forward against the door, which in turn swung into the room and sent him careening downward, his flashlight falling from his grasp and clattering to a halt at the base of Toriel’s chair as his chin made contact with the ground below.

Toriel rose with a start, a hand to her chest as she watched Frisk fall to the floor. She sighed with relief and panic as she scurried over to help her child up, bringing him to her bed as she wiped tears away from his eyes. The impact with the floor had left a small bruise on his chin, and she gently nursed him as he calmed himself down, enjoying her loving embrace.

When he had finally calmed down, she looked down at him with a soft smile. “Now…what are you doing up this late, little one?” She stroked the top of his head sweetly.

“I…I thought I heard a noise, and I wanted to make sure you were okay,” Frisk stated, blushing slightly at his subterfuge being discovered.

“Oh, you’re sweet, young child,” Toriel stated, placed her hand on his cheek. “I’m alright, I promise. Just…thinking about something that happened a long time ago. I got a little sad and…well…” She looked away from him, her smile fading. She stared into the space in front of them, a single tear streaming down her face. “It’s all in the past now, I suppose…”

“Who were the others?”

Toriel looked down at him quizzically. “The others?”

“In the photos. The large Goat man and the small boy and…the other Human…”

“Oh, my dear…” She motioned for him to stay before standing, gathering up all the photos and bringing them with her as she sat down beside him once more. “This is Asgore,” Toriel began, pointing to the large Goat man. He had a friendly smile and sad eyes, but he looked like a friendly sort. “And these young ones right here are my children, Asriel and Chara…” Asriel’s goofy smile radiated sunshine, and Chara side eyed the young goat boy with a half-smile. “It’s been so long since we were a family, and I guess I just got lost thinking about them…”

“What happened?”

She looked down at him with a smile. “…That’s not important. What IS important is that you should be in bed, young man.”

“I couldn’t sleep…”

“Than you can sleep with me tonight if you like. You just need to promise me you’ll do your best to sleep so that we can have some fun together tomorrow.”

Frisk smiled and nodded, and the two of them crawled under the covers together. Toriel wrapped an arm around Frisk, who gently cuddled up next to her, his head resting on her breast as her steady heartbeat helped him calmly drift off to sleep.

Before he fell to sleep for the night, Frisk sleepily looked up at his adoptive mother, and made a silent promise to himself. Toriel was his mother now…and he would do whatever it took to make her feel happy again.

-X-

The next few weeks went by with the same routine as usual. Twice a week they would forage, they’d share meals together, and they would sit by the fire as they shared pie each night. But now the nights were filled with stories of Toriel’s former life with her family, and Frisk listened intently to each one.

He learned that she had wanted to be a teacher, to share her intellect with a new generation of young minds. He learned about her love of yellow flowers, how she used to playfully torture her family with the same awful puns she now joyously shares with him, and that she wasn’t just a lost mother in the Underground.

Apparently, Asgore was the king of the Underground, and after they lost their children to some hardship she wouldn’t share, Asgore became obsessed with returning to the surface, wanting to exact revenge on the Humans who had trapped them down here. She warned him about the dangers of the Underground beyond a barrier found deep within their basement, and he promised to never leave her side for fear of being hunted down by Asgore and those loyal to him.

The more she talked of Asgore, the more Frisk could hear the contempt in her voice, like even just speaking his name brought her to the brink of anger. He still wasn’t entirely sure what had happened between them, but none of that mattered to him; Asgore had hurt Toriel, and that was all Frisk needed to know to despise him as well.

As the weeks rolled on Frisk made good on his promise, making sure to help out wherever he could around the house. He would help with the dishes without prompting, would go out foraging on his own so Toriel could rest when she wasn’t feeling her best, and even stomached eating some Snail Pie on more than one occasion. The more he ate it the easier it became, but he always made sure to finish each half-slice just to see the warm smile Toriel would give him. Every time she would praise him for helping, he would simply reply by letting her know that he wanted her to be happy.

She too had begun to become a little more attentive to his needs. Each night she would sit with him in his bed, telling him stories about her former life and of the many things she knew as she stroked his head. She would join him occasionally for a bath, helping to scrub his harder to reach places and occasionally splash him playfully with the water, the two of them naked together with nothing to hide from one another. And more often lately, she asked him to sleep in her bed, the two of them holding one another tightly as if they feared they would drift off into space if they let go. Each night, Toriel would kiss him gently on the forehead, regardless of whether they shared a bed or not, and tell him softly that she wanted him to be happy too.

Frisk had long since abandoned any hope or desire of leaving, and now he was utterly devoted to his new mother. He was happy, and he hoped beyond hope that she was too.

-X-

Frisk awoke late one quiet night to the sound of a ghostly wail. He clambered for his flashlight, illuminating the dark room in a sleep induced panic. As his mind woke up more and his eyes adjusted to the dark, he realized that there was no ghost, but instead he was hearing Toriel again like he had weeks before. He felt his heart drop at the thought of her still being sad, and with determination stood up and went to investigate.

Tip-toeing through the hallway to try and avoid detection, he stopped at her door and gently opened it, peering into the dark room. Almost immediately he was met by the sound of Toriel, but she sounded different than when he had caught her crying. She was breathing heavily, an occasional moan escaping her lips. He also heard the soft sound of something wet being moved about…

Frisk wasn’t entirely sure what was happening, but he opened the door further to investigate. His eyes shot open with surprise when he saw Toriel on her bed, stripped of any clothing and three of her fingers plunged deep into the wet walls of her pussy, her free hand rubbing one of her large furry breasts.

Frisk watched was she massaged her breast and twisted her wrist, pleasing her long ignored body and enjoying even the simplest of movements. Her fingers drove themselves in and out, mimicking the feeling of something ramming into her with borrowed accuracy. Her mouth hung open, her soft breath letting out small moans of pleasure as she dug deeper into herself.

Frisk wasn’t sure what was happening, but he felt a strange feeling well up inside of him. The more he watched, the more he found himself enjoying the sight, but couldn’t quite place the feelings such a show was giving him. He felt happy and warm, and soon realized that at least part of that warmth was coming from his pants.

Looking down, he could see that his cock was erect, twitching slightly as it brushed up against his pants. He quickly and quietly removed them, perplexed by how stiff it had become from watching his mother. He hesitantly reached down and grabbed hold of it, and a whole new explosion of feelings erupted with in, his hot member overtaking his mind and begging to be touched and stroked.

His attention turning back to his mother, Frisk enjoyed his first ever masturbation session, watching his finger herself as he stroked his cock diligently. His breathing became more ragged as he continued, watching now as Toriel let go of her breast and plunged fingers from her other hand into her pussy, filling her hole with as much as it could fit.

The two of them continued like this for some time, Toriel blissfully unaware of Frisk’s presence as he masturbated in the doorway. Toriel began to speed up her movements, plunging in deeper as her moaning grew louder. She took one of her nipples into her mouth as she did, suckling the tit as she fingerbanged herself to orgasm.

Her hips arched up as she exploded with pleasure, sending a stream of juices forcibly into the air. Her moans were caught in her throat as she silently cried out with joy, and after about ten seconds she slumped back down on the bed, her arms at her side and a dopey smile plastered across her face.

Frisk stood there, as still as the dead and daring not to move, watching as Toriel slowly sat up. She looked around the room, stretched her arms above her head and yawned, and grabbed a glass of water off her nightstand. He watched her take a drink, and even then he was perplexed by how much it affected him. He’d seen her drink water more times than he could think, but something about the way she was doing it now made him hot and heavy.

He involuntarily made a noise, and too late realized that it had been a tad bit too loud. Toriel jumped with a start and turned to look at him, covering herself when she realized Frisk was there.

“Frisk?!” She shouted, grabbing the blankets to cover her. “Honey, what’s wrong?!”

“I, uh…” Frisk stammered as he entered the room. Toriel saw that he was pantless and erect, her eyes wide as she looked down at his erect cock then back up at him.

“Oh, my sweet child,” she said, a soft smile crossing her face as she lowered the blanket slightly. “I understand what’s happening. Come here…” She waved him over, patting the bed beside her. Frisk walked hesitantly across the bedroom, staring at the floor. He casually jumped onto the bed, still looking away from her, but she just smiled all the same.

“My big boy,” she said, lacing her fingers through his hair. “You’ve been growing up so quickly and I hadn’t even noticed…”

“Am I in trouble?” Frisk asked, finally looking up at her.

“Child, why would you think you’re in trouble for this?”

“I was peeking in on you doing…something…”

“What I was doing, dear, was pleasuring myself.” Frisk looked up at her with confusion. “While I’ve been telling you about my former life, it’s brought up many memories of when I was younger…and desirable…I would spend my days with my two children, but at night…Asgore and I would become one together…It’s a beautiful thing when two souls become one…”

“Is that what you were doing with your fingers, then?”

Toriel chuckled. “Something like that…But I can see that you understand that to some degree,” she stated as she motioned towards his still erect cock. Frisk’s face went red as he covered himself and looked away, but Toriel just laughed. “No need to cover yourself, my child. You have nothing to hide from mommy.”

Toriel moved his hands, and smiled to herself. His cock wasn’t very large, but he also only a young child, no more than 13. Even still, she was impressed at how rigid it was…and how it made her feel…She caught her breath in her throat before clearing it, regaining some composure.

“That is nothing to be ashamed of, my child. It merely means that you enjoyed what you saw…And that makes me happier than you could possibly imagine…”

Frisk looked up her once more. “You’re really happy by this?”

“I really am.” She pulled him in close and kissed his forehead tenderly, and an idea popped into her head. “But…I can think of a way you might make mommy happier.”

“Anything for you…Mom…”

She smiled. “That’s my boy.”

She repositioned herself on the bed, resting her back against her many pillows and spreading her legs wide. She motioned for Frisk to sit in front of her, and she pulled apart her walls, letting him see inside of her. “This is my vagina, Frisk. I want you to think of this like a keyhole, and your penis is the key. You want to unlock my true happiness, my child? Than stick your key in here and make mommy the happiest Monster in the Underground.”

Frisk wasn’t sure what to do. Part of him felt like this was somehow wrong…like it was forbidden. But his cock twitched with anticipation, and he felt a warmth within him that he had never felt before. It reminded him of the warmth he had when he first saw he…pleasing herself…and he decided that he enjoyed that warmth. Plus, it would make his mother happy…and he wanted nothing more than for her to be happy.

Frisk got up more on the bed, positioning himself in front of Toriel. She stared at him with hungry, wanting eyes, her gaze shifting naturally between his cock and face. He grabbed hold of her legs gently, and the touch sent a shiver throughout Toriel. She moaned with approval, spreading her legs a little wider and scooting closer to him.

“Please, baby. Mommy needs you inside of her.”

Frisk’s hesitation left him, and without a moment to lose her moved forward, the tip of his cock at her entrance. She gasped with anticipation, wrapping her hands around him and she helped to guide him in slowly, moaning with glee as she felt him enter her.

Frisk felt instant relief, his erect and throbbing cock feeling the inside of a woman for the first time. It was warm and inviting, and he wanted nothing more in the world than to find someway to stay there for the rest of time. The amount of pleasure coursing through him was so great, so all encompassing, that he felt the pressure in his cock leave him as he came for the very first time.

Toriel cried out in shock and joy as she felt him fill her. Frisk reacted with horror, thinking he had just peed inside his mother, and as he tried to back out Toriel simply held him there, embracing him with a smile and a soft kiss to the cheek.

“My boy,” she said, staring into his eyes.

“I’m so sorry, mom! I didn’t know…I don’t…”

“It’s alright, dear,” she said lovingly, stroking his hair and reassuringly shushing him. “All that’s happened is you came for mommy…and Mommy very much enjoys that you did.”

“What do you mean…came?”

“Men have within them a sort of…love juice,” she stated, hoping to reassure him. “It comes out of the same place you pee from, yes, but it very much is not the same. What you’ve done is released some of that Love juice into me, which only goes to show that you love your mother very much.”

Frisk smiled. He did love his mother, and the lose of pressure had felt good… “So, what happens now, mom?”

“Well, that’s up to you, dear. We can continue with this course of action, or we can stop. How do you feel?”

“I feel…warm…and full of love for you.”

She smiled, wiping away a tear of joy. “Do you want to continue?”

“Yes, please, Mom.”

“Then move your hips back and forth to make your penis move inside of me. It’ll make us both feel good, and you’ll make more love juice come out in time.”

Frisk wasted no time, his hips moving the second she told him to. It was slow at first as he adjusted to the awkward motions, but once he got used to it he was moving at a good pace, sending his cock in and out of her wet walls. Toriel responded by gasping with joy, bringing Frisk’s face down in between her breasts as she willed him to continue.

Frisk loved the feeling of his cock entering and exiting his mother’s pussy, the warmth of it on his cock and the sound of her increased breathing as she lovingly held onto him. His mind was awash with emotions as the sensations filled him for the first time, giving him a whole new perspective on his relationship with Toriel and what might come next for the two of them.

He began to pick up the pace a little, finding that the faster he went the more he enjoyed it. Toriel responded in turn by breathing faster and giving him more words of encouragement, one of her hands absentmindedly going down to his bottom and helping him to push deeper into her. She knew it wouldn’t reach the inner most parts of her, but every inch of him within her made her feel loved, and she wanted as was possible.

Frisk shrugged off the hand holding him between her breasts and propped himself up, using the extra leverage to push into her even faster and harder. Toriel placed a hand on his cheek and smiled, still crying out with joy as he adoptive son fucked her. Frisk stared up at his mother, love filling her gaze, and he felt a pressure building up in his lower half again.

“Mom…I’m feeling it again…I think I’m close to…”

“It’s okay, baby,” Toriel stated, placing both hands on his behind and helping him to push deeper in still. “I want your love juice! Give me your love juice!”

Frisk pumped three of four more times before he felt the release, sending another shot of cum into Toriel. At the same time, she let her head fall back, enjoying the warmth of his cum inside of her and she held him as close to her as she could. Frisk unloaded everything he had into her, and when he was done he felt the life drain from his body, slumping down on top of Toriel and resting his head between her breasts.

Toriel simply began to stroke his hair once more, looking down at him with love. “Do you feel better now, my child?”

“I do, mom,” Frisk said between breaths. He propped himself up to look at her. “How about you?”

“My dear boy, you’ve made me feel happier than I’ve felt in a long time.” She embraced him with a powerful hug, one that his exhausted body lazily reciprocated. They sat for a while just enjoying the feeling of warmth the other gave off, knowing that their relationship had grown immensely thanks to the union of the flesh.

When Frisk finally moved himself off of Toriel, he stretched and yawned with great emphasis. Toriel simply shifted in the bed to let him sleep next to her, and the two happily dozed off, having shared the first of many nights together. Frisk was out within seconds, the warm embrace of Toriel cradling him lovingly, and as she watched her new lover sleep beside her, Toriel felt for the first time that leaving Asgore had been the right thing.

After all…it had brought her her dear sweet Frisk.

**Author's Note:**

> I have a Twitter! You can commission work or just see some of the things I'm into there!
> 
> @Sir_Skullian  
> https://twitter.com/Sir_Skullian


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